1. Field of the Invention
This disclosure relates to firearms in general, and more particularly, to sound (e.g., noise) suppressors for firearms.
2. Related Art
Firearms, such as pistols or rifles, utilize expanding high-pressure gases generated by a burning propellant to expel a projectile from the weapon at a relatively high velocity. When the projectile, or bullet, exits the muzzle end of the weapon's barrel, a bright, “muzzle flash” of light and a high-pressure pulse of combustion gases accompany it. The rapid pressurization and subsequent depressurization caused by the high-pressure pulse gives rise to a loud sound known as “muzzle blast,” which, like muzzle flash, can readily indicate to a remote enemy both the location of the weapon and the direction from which it is being fired. In some situations, such as covert military operations, it is highly desirable to conceal this information from the enemy by suppressing the flash and/or eliminating or substantially reducing the amplitude of the muzzle blast.
The use of sound suppressors (e.g., also referred to as noise suppressors and silencers) on firearms to reduce the amplitude of their muzzle blasts is known. Suppressors operate to reduce muzzle blast by reducing and controlling the energy level of the propellant gases accompanying the projectile as it leaves the muzzle end of the weapon. These devices typically include an elongated tubular housing containing a series of baffles that define a plurality of successive internal chambers. These chambers serve to control, delay, and divert the flow, expansion, and exiting of the propellant gases, and also to reduce their temperature, so as to achieve a corresponding reduction in the noise produced by the propellant gases as they ultimately exit the device. The rear (e.g., proximal) ends of these suppressors typically include a mechanism for removably attaching the device to the weapon, and their front (e.g., distal) ends include an opening for the exit of the projectile, and are typically located sufficiently forward of the muzzle end of the weapon that they also can effectively function as a flash hider (e.g., a muzzle flash suppressor).
In one classification scheme, silencers for firearms can be divided into two groups. In one group, the gases that follow the bullet into the rear end of the silencer are stored for a short period of time in each of a plurality of successive expansion chambers so as to produce a controlled expansion of the propellant gases through each chamber, thereby reducing their temperature and pressure in successive, gradual stages.
In a second group, at least a portion of the propellant gases are partially diverted through a plurality of radial vents or passages disposed between inner and outer circumferential walls of the suppressor to one or more un-baffled, radially exterior “blast suppressor” chambers located in a back section of the device, before being introduced into the series of expansion chambers of a baffled “front section” of the device of the type described above. Although this “two-stage” sound suppression technique is relatively more complex to implement, it provides more opportunities to delay and cool the propellant gases, and hence, to reduce muzzle blast sound levels overall.
Existing suppressors have certain problems that can mitigate their operation and/or efficiency. For example, as those of skill in the art will understand, since a suppressor operates by controllably containing the hot, expanding combustion gases used to propel the projectiles of the weapon upon which it is used, with extended use of the device over time, particulate contaminates contained in the combustion gases will condense and be deposited over the interior surfaces of the device, including the surfaces of the baffles. These deposits include carbon from the burnt propellant, lead from the projectiles, and in the case of the use of “jacketed” projectiles, copper, Teflon, and/or molybdenum disulfide. While these deposits can usually be cleaned away with suitable solvents, they are typically hard and adhesive in nature, making it difficult or impossible to disassemble the device for cleaning without damaging its parts.
Another problem associated with certain suppressors occurs where front and rear ends of a suppressor are both implemented using end caps that are secured to a housing with threaded joints. The rear end cap typically includes an internally threaded bore that is used to screw the suppressor onto an adapter, e.g., a flash hider, a muzzle brake, or directly onto a muzzle of the associated firearm to secure the suppressor thereto. Unfortunately, this arrangement can complicate the removal of the suppressor from the firearm because, as the suppressor is unscrewed from the adapter or the muzzle, the torque exerted by the user on the suppressor housing can cause the rear end cap of the suppressor to unscrew from the housing, rather than from the adapter or muzzle of the firearm. This may cause the rear end cap to remain substantially fixed on the adapter or muzzle. As a result, the suppressor may separate and become difficult to detach completely from the firearm.
Another problem that can occur particularly with the “two-stage” type of silencers described above relates to the fact that the first stage, “blast suppressor” back sections of the devices typically experience substantially greater radial pressures and temperatures than the baffled front compartments of the devices during the firing of a single round through the device. While this does not ordinarily present a problem when the weapon is fired intermittently, with sufficient time allowed between rounds to permit the pressure and temperature within the back section to abate, it can present a problem with sustained firing of the weapon at a relatively high rate of fire, e.g., during sustained, full automatic fire of the weapon. In such instances, it is possible for the outer tubular housing of the device to fail prematurely, i.e., to “blow out,” due to the sustained local pressures and temperatures impinging directly thereon during such sustained, full automatic, high rates of fire. One unsatisfactory approach to solving this problem is to increase the overall thickness of the external housing of the suppressor. However, such an approach may significantly increase the weight of such suppressors and torque exerted on a weapon, thus hampering their usefulness.
Another problem with existing suppressors relates to their ability to function effectively as muzzle flash suppressors. While the distal, or exit end of a prior art silencer is typically disposed forward of the actual muzzle end of the weapon's barrel, it is nevertheless possible for the suppressor to exhibit a relatively large muzzle flash when a “first round” is fired through the device (e.g., when the suppressor has not been recently fired). “Second” and immediately subsequent rounds fired from the suppressor typically do not exhibit this relatively large muzzle flash.
Another problem with existing suppressors relates to the mechanisms used to couple them to firearms. Such mechanisms typically include an internal mounting pin disposed in the suppressor that engages in a slot at the end of an adapter, which can comprise a flash hider or muzzle brake mounted at the muzzle end of the barrel of the firearm to which the suppressor is to be removably coupled. This arrangement can be problematic for several reasons. For instance, the mounting pin is cumbersome to manufacture, is prone to breakage, and cannot be easily repaired. Further, both the pin in the suppressor and the corresponding slot in the adapter are typically positioned well within the suppressor and, therefore, are subject to a buildup of carbon, lead and copper during firing use, as described above, which can complicate disassembly and prevent proper alignment and/or seating of the adapter within the suppressor.